Air and moisture stable high capacity cathode materials for sodium ion batteries

Abstract

The present invention relates to a sodium ion battery comprising a positive electrode composition having improved battery performance and moisture and air stability. The positive electrode composition has the general formula NaxAzNiiMyMnjTikSbfO2, where A is an alkali metal or alkaline earth metal selected from Ca, Li, M is a divalent element or trivalent element selected from Fe, Mg, Zn, Cu, Al, Co, and Ni is a divalent element, Mn, Ti are tetravalent elements, and Sb is a pentavalent element / trivalent element, where (i + j + k + f + y = 1), 0.7 < = x < = 1, 0 < = z < = 0.2, 0.1 < = i < = 0.6, 0 < = y < = 0.5, 0.1 < = j < = 0.5, 0.05 < = k < = 0.4, and 0 < = f < = 0.2. The invention is suitable for energy storage application.

Description

Technical Field

[0001] The present invention relates to a sodium ion battery comprising a positive electrode composition having improved battery performance and moisture and air stability. More specifically, the present invention relates to manganese transition metals and other transition metals, such as Ni and Fe, as well as Ca, Cu and Ti, which are incorporated into the sodium structure to obtain better air and moisture stability. In addition, the present invention relates to a sodium ion battery having the general formula Na x A z Ni i M y Mn j Ti k Sb f A composition of O2, wherein A is an alkali metal or alkaline earth metal selected from Ca and Li, M is a divalent element or a trivalent element selected from Fe, Mg, Zn, Cu, Al, and Co, Ni is a divalent element, Mn and Ti are tetravalent elements, and Sb is a pentavalent element / trivalent element, wherein (i+j+k+f+y=1), 0.7≤x≤1, 0≤z≤0.2, 0≤y≤0.5, 0.1≤i≤0.6, 0.1≤j≤0.5, 0.05≤k≤0.4, and 0≤f≤0.2. The present invention relates to grid energy storage applications. Background Art

[0002] Large-scale energy storage systems have recently attracted increasing attention. However, the Earth's relatively low abundance and uneven distribution of lithium, cobalt, and nickel resources are insufficient to meet the growing demand for these systems. Sodium-ion secondary batteries (NIBs) are a potential alternative to lithium-ion secondary batteries. Due to the abundance and widespread distribution of sodium resources, high demand and cost considerations may necessitate the use of sodium-ion batteries (NIBs) rather than lithium-ion batteries. In many respects, sodium's electrochemical behavior is similar to that of lithium.

[0003] According to the coordination environment of sodium ions in the structure, Na x TMO2 (where TM is a transition metal, such as Co, Ni, Mn, Fe, and Cu) can be broadly classified into P-type (prismatic coordination) and O-type (octahedral coordination), with P2 and O3 phases being the most common structural types. Various types of potential cathode materials have been investigated, including transition metal oxides, Prussian blue analogs, and polyanionic compounds. Among them, layered transition metal oxides are highly favored due to their ease of synthesis, high energy density, and ease of large-scale production.

[0004] One of the key issues with layered oxide cathode materials is air and moisture stability. Air-sensitive materials require special manufacturing conditions; they must be prepared, stored, and assembled in a dry or even inert environment, which inevitably increases costs. Since the target application of sodium-ion batteries is large-scale grid energy storage systems, cost is the most important factor. We need an effective technology that allows the cathode to have water-treatable properties. In order to promote the practical application of sodium-ion batteries, it is necessary to understand and solve the problem of their poor air and moisture stability. This problem is solved in the present invention.

[0005] In this paper, we propose a key strategy to improve the air and moisture stability of cathode materials. By substituting elements at transition metal or sodium sites, reducing the sodium content, and increasing the open-circuit voltage, the layered material achieves oxidative stability. The introduction of copper, calcium, and titanium is crucial for improving air and moisture stability and further maintaining specific capacity values ​​in the 120 to 140 mAh / g range.

[0006] Refer to Feng Lin et al Journal of The Electrochemical Society 2019, 166(2)A251-A257, which reported a material P2-Na 0.67 Ni 0.22 Cu 0.11 Mn 0.56 Ti 0.11 O2 and its performance under water treatment conditions. The material achieved 180mAh g at 22℃ -1 The discharge capacity and 544Wh kg -1 discharge energy. Aging experiments showed excellent water stability with negligible changes in bulk structure or chemistry. However, the P2 phase lacks sodium, and it is impractical to fabricate a full battery without using a sodium-containing negative electrode material. In addition, the high specific capacity in this composition is attributed to the manganese redox occurring below 2V. Surface-sensitive soft X-ray absorption spectroscopy showed that the cathode had a stable surface chemistry in aqueous solution. In addition, the battery with the water-treated cathode exhibited stable cycling performance with smaller voltage decay originating from the reduced cell impedance.

[0007] Reference can be made to Mark N. Obrovac et al, ACS applied materials and interfaces 2018, 10, 44, 38246–38254, which reported a detailed study of NaNi by XRD structural analysis, SEM imaging, FTIR spectroscopy surface analysis, and electrochemical measurements. 0.5 Mn 0.5O2 sensitivity to air exposure. 0.5 Mn 0.5 The reaction that occurs when O2 is exposed to air is complex. 0.5 Mn 0.5 O2 completely destroyed the structure, while washing with ethanol did not cause significant structural damage. In contrast, ethanol washing removed NaNi 0.5 Mn 0.5 Most of the sodium residues on the O2 surface.

[0008] Reference can be made to Yunming Li et al advanced sciences 2015, 2(6): 1500031, which designed a new type of air-stable positive electrode. 7 / 9 Cu 2 / 9 Fe 1 / 9 Mn 2 / 3 Electrochemical performance of O2 as a cathode material for rechargeable sodium-ion batteries. The material exhibited 89 mAh g at a 0.1C rate. -1 The attractive performance is the long-term cycling stability, as evidenced by the 85% capacity retention after 150 cycles at 1C rate without phase transition. When combined with a hard carbon anode, it exhibits 313 mAh g -1 High reversible capacity, high initial Coulombic efficiency of 79% and 195Wh kg at 0.2C rate -1 The high energy density shows good application prospects.

[0009] Reference can be made to Shi-Xue Dou et al Advanced energy materials.2018,8,1701610, which reported a new type of air-stable O3-type Na[Li 0.05 Mn 0.50 Ni 0.30 Cu 0.10 Mg 0.05 ]O2 cathode, which was synthesized by a co-precipitation method followed by high-temperature annealing. It exhibited 172 mAh g at 0.1C. -1 The reversible capacity of the 200 nm CMOS process was 215 Wh kg-1 at 0.1 C, and the capacity retention was 70.4% after 1000 cycles at 20 C. More importantly, it showed good compatibility with the original hard carbon as the negative electrode in the sodium-ion full battery. -1 High energy density and good rate performance.

[0010] Reference can be made to Yu - Guo et al, Journal of American Chemical Society 2017, 139, 25, 8440–8443, which reported a combined structural regulation strategy to improve the air stability of O3 - type cathode materials by reducing the interlayer distance of the sodium layer and simultaneously increasing the valence state of transition metals. Through the co - doping of copper / titanium in the cathode NaNi 0.5 Mn 0.5 O2. The obtained NaNi 0.45-x Cu 0x Mn 0.4-y Ti y O2, where 0.05 ≤ x ≤ 0.1, 0 ≤ y ≤ 0.1, the stable aeration time is increased by 20 times, the capacity retention rate after 500 cycles is increased by 9 times, and even after being soaked in water, it still maintains its original structure and capacity.

[0011] Reference can be made to Patent WO 2016 / 188877. The present invention describes the application of specific divalent metal ions, more specifically any one or more of Cu, Ni, and Zn doping, to sodium cathode materials to provide sodium - ion batteries with excellent rate performance and long cycle life. The cathode has the composition Na x M y Mn 1-y Li y’ A z O2 or Na x M y Mn 1-y O2, where 0.60 < x < 0.95, M is composed of one or more elements from the group consisting of Cu, Zn, and Ni, 0.05 ≤ y < 0.20, A is composed of one or more elements from the group consisting of Mg, Ti, Fe, Cr, and Co, 0 ≤ z < 0.2, 0 ≤ y' < 0.33, and z + y' > 0. The present invention also provides a method for preparing sodium - layered oxide materials and their applications.

[0012] Reference can be made to Patent US2022 / 0013772 A1. The present invention relates to a cathode material for sodium - ion batteries. The cathode active material for sodium - ion batteries has the following formula: Na x Ni 0.5-y Cu y Mn 0.5-z Ti z O2, where, - x is 0.9 to 1; - y is 0.05 to 0.1; - Z is 0.1 to 0.3. When z is equal to 0.1 and x is equal to 1, then y is not equal to 0.05. The present invention relates to a method for producing a sodium metal oxide composition protected by the claims. Finally, the present invention also relates to a specific cycling method for sodium - ion batteries containing a specific cathode active material.

[0013] Therefore, considering the shortcomings of the prior art reported so far, the provision of multivalent layered oxide compositions is expected to improve cathode material characteristics in terms of capacity performance, average operating voltage, cycle life, structural stability, moisture and air stability, and large-scale production. Purpose of the Invention

[0014] The main purpose of the present invention is to develop a high-capacity, low-cost, moisture- and air-stable cathode material for sodium-ion battery applications.

[0015] Another object of the present invention is to provide a multivalent positive electrode composition wherein the elements are selected in such a way that the combination of elements will provide enhanced structural, thermal, air and moisture stability, higher average potential, higher redox which contributes to increased capacity, and enhanced sodium ion diffusion kinetics.

[0016] Another object of the present invention is to provide a low-cost electrode containing active materials that are simple to prepare and easy to handle and store.

[0017] Another object of the present invention is to incorporate small amounts of Ca and Cu into transition metal sites at the sodium sites, which improves structural stability, moisture and air stability.

[0018] Another object of the present invention is to use high-price elements such as Sb in the structure +5 To stabilize the 3d metal in a lower valence state, thereby utilizing M +2 / M +3 / M +4 The complete redox reaction of antimony oxide leads to higher specific capacity values. The further glass-forming property of antimony oxide contributes to the easy synthesis and pure phase formation.

[0019] Another object of the present invention is to provide a sodium metal oxide composition as a positive electrode for sodium ion batteries that is lower in cost than prior art compositions and is easier to produce on a large scale. Summary of the Invention

[0020] In the present invention, alkali metals and alkaline earth metals and transition metals are used to obtain sodium cathode materials with high capacity, moisture and air stability. The composition has the general formula Na x A z Ni i M y Mn j Ti k Sb fO2, wherein A is an alkali metal or alkaline earth metal selected from Ca and Li, M is a divalent element or a trivalent element selected from Fe, Mg, Zn, Cu, Al, and Co, and Ni is a divalent element, Mn and Ti are tetravalent elements, and Sb is a pentavalent element / trivalent element, wherein (i+j+k+e+y=1), 0.7≤x≤1, 0≤z≤0.2, 0≤y≤0.5, 0.1≤i≤0.6, 0.1≤j≤0.5, 0.05≤k≤0.4, and 0≤f≤0.2. According to an embodiment of the present invention, the concentration of the element Na'x' may be in the range of 0.7 to 1, the concentration of the element A'z' may be in the range of 0 to 0.2, the concentration of the element Ni'i' may be in the range of 0.1 to 0.6 and is a divalent element, the concentration of the element M'y' may be in the range of 0. to 0.5 and is a divalent element or a trivalent element selected from Fe, Mg, Zn, Cu, Al, Co, or a combination thereof. The concentration of the element Mn'j' may be in the range of 0.1 to 0.5 and is a tetravalent element, the concentration of the element Ti'd' may be in the range of 0.05 to 0.4 and is a tetravalent element, and the concentration of the element Sb'f' may be in the range of 0 to 0.2 and is a pentavalent element / trivalent element (wherein the values ​​of x, i, j, k, f, and y are selected to ensure that the material as a whole remains electrically neutral).

[0021] According to an embodiment of the present invention, the composition is synthesized by a simple solid-state method.

[0022] According to an embodiment of the present invention, the cathode material composition exhibits good cycle stability, high operating voltage, and good rate capability.

[0023] According to an embodiment of the present invention, the composition is a single-phase O3-type layered structure with a space group of R-3m.

[0024] In one aspect of the present invention, the voltage window of the positive electrode active material composition is in the range of 2V to 4.4V.

[0025] In another aspect of the present invention, the capacity of the positive electrode material composition is in the range of 70 mAh / g to 195 mAh / g.

[0026] In another aspect of the present invention, the positive electrode material composition has a morphology of irregular particles, flaky particles, hexagons, cubes, spheres, and elongated hexagons.

[0027] In another aspect of the present invention, a sodium ion battery (100) comprises: a dual-phase multivalent layered oxide positive electrode material composition (106) coated with aluminum foil; a negative electrode (102) coated with aluminum foil; an electrolyte (108) and a porous separator (104).

[0028] These and other advantages will be apparent from the embodiments of the present application described herein.

[0029] The foregoing is a simplified overview to provide an understanding of some embodiments of the present invention. This overview is neither a comprehensive overview nor an exhaustive overview of the present invention and its various embodiments. The summary of the invention illustrates selected concepts of embodiments of the present invention in a simplified form as an introduction to the more detailed description presented below. It will be understood that other embodiments of the present invention may utilize one or more of the features described above or in detail below, alone or in combination. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The foregoing and other features and advantages of embodiments of the present invention will become apparent upon consideration of the following detailed description of embodiments of the present invention, particularly when considered in conjunction with the accompanying drawings, in which:

[0031] Figure 1 A schematic diagram of a sodium ion battery according to an embodiment of the present disclosure is shown.

[0032] Figure 2A The Na according to the embodiment of the present disclosure is shown 0.97 Ca 0.03 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05 X-ray diffraction pattern of the O2 cathode material composition.

[0033] Figure 2B The water-treated Na 0.97 Ca 0.03 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05 X-ray diffraction pattern of the O2 cathode material composition.

[0034] Figure 2C The Na according to the embodiment of the present disclosure is shown 0.98 Ni 0.25 Cu 0.091 Mn 0.375 Ti 0.2 Sb 0.0833 X-ray diffraction pattern of the O2 cathode material composition.

[0035] Figure 2D The water-treated Na 0.98 Ni0.25 Cu 0.091 Mn 0.375 Ti 0.2 Sb 0.0833 X-ray diffraction pattern of the O2 cathode material composition.

[0036] Figure 2E The Na according to the embodiment of the present disclosure is shown 0.96 Ca 0.04 Ni 0.25 Cu 0.125 Mn 0.375 Ti 0.166 Sb 0.083 X-ray diffraction pattern of the O2 cathode material composition.

[0037] Figure 2F The water-treated Na 0.96 Ca 0.04 Ni 0.25 Cu 0.125 Mn 0.375 Ti 0.166 Sb 0.083 X-ray diffraction pattern of the O2 cathode material composition.

[0038] Figure 2G The Na according to the embodiment of the present disclosure is shown 0.8 Ca 0.2 Ni 0.6 Mn 0.2 Ti 0.2 X-ray diffraction pattern of the O2 cathode material composition.

[0039] Figure 2H The water-treated Na 0.8 Ca 0.2 Ni 0.6 Mn 0.2 Ti 0.2 X-ray diffraction pattern of the O2 cathode material composition.

[0040] Figure 2I The NaNi according to the embodiment of the present disclosure is shown 1 / 6 Mg 1 / 6 Cu 1 / 6 Co 1 / 6 Fe 1 / 6 Mn 1 / 8 Ti 1 / 8 X-ray diffraction pattern of the O2 cathode material composition.

[0041] Figure 2J The water-treated NaNi according to an embodiment of the present disclosure is shown. 1 / 6 Mg1 / 6 Cu 1 / 6 Co 1 / 6 Fe 1 / 6 Mn 1 / 8Ti 1 / 8 X-ray diffraction pattern of the O2 cathode material composition.

[0042] Figure 2K The Na according to the embodiment of the present disclosure is shown 0.95 Ca 0.05 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05 X-ray diffraction pattern of the O2 cathode material composition.

[0043] Figure 2L The water-treated Na 0.95 Ca 0.05 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05 X-ray diffraction pattern of the O2 cathode material composition.

[0044] Figure 2M Shows Na 0.95 Ca 0.05 Ni 0.6 Mn 0.2 Ti 0.1 Sb 0.1 X-ray diffraction pattern of O2.

[0045] A positive electrode material composition according to an embodiment of the present disclosure.

[0046] Figure 2N The water-treated Na 0.95 Ca 0.05 Ni 0.6 Mn 0.2 Ti 0.1 Sb 0.1 X-ray diffraction pattern of the O2 cathode material composition.

[0047] Figure 2O The Na according to the embodiment of the present disclosure is shown 0.96 Ca 0.02 Ni 0.45 Cu 0.1 Mn 0.25 Ti 0.1 Sb 0.1X-ray diffraction pattern of the O2 cathode material composition.

[0048] Figure 2P The water-treated Na 0.96 Ca 0.02 Ni 0.45 Cu 0.1 Mn 0.25 Ti 0. 1Sb 0.1 X-ray diffraction pattern of the O2 cathode material composition.

[0049] Figure 2Q The Na according to the embodiment of the present disclosure is shown 0.97 Ca 0.03 Li 0.02 Ni 0.5 Cu 0.05 Mn 0.2 Ti 0.1 Sb 0.13 X-ray diffraction pattern of the O2 cathode material composition.

[0050] Figure 2R The water-treated Na 0.97 Ca 0.03 Li 0.02 Ni 0.5 Cu 0.05 Mn 0. 2Ti 0.1 Sb 0.13 X-ray diffraction pattern of O2 material composition.

[0051] Figure 2S The NaCu according to the embodiment of the present disclosure is shown 0.1 Ni 0.15 Fe 0.30 Mn 0.35 Ti 0.05 Sb 0.02 X-ray diffraction pattern of the O2 cathode material composition.

[0052] Figure 2T The aqueous treated NaCu according to an embodiment of the present disclosure is shown. 0.1 Ni 0.15 Fe 0.30 Mn 0.35 Ti 0.05 Sb 0.02 X-ray diffraction pattern of the O2 cathode material composition.

[0053] FIG3A shows a method for producing a molten salt solution using Na according to an embodiment of the present disclosure. 0.97 Ca 0.03 Ni 0.4Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.0 Voltage-time curve of sodium half-cell made of 5O2 positive electrode material.

[0054] Figure 3B The Na washed with positive water according to the embodiment of the present disclosure is shown. 0.97 Ca 0.03 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05 Capacity-cycle number curve of sodium half-cell made of O2 material.

[0055] Figure 3C The method of using Na according to an embodiment of the present disclosure is shown. 0.98 Ni 0.25 Cu 0.091 Mn 0.375 Ti 0.2 Sb 0.0833 Voltage-time curve of sodium half-cell made of O2 positive electrode material.

[0056] Figure 3D The method of using Na according to an embodiment of the present disclosure is shown. 0.98 Ni 0.25 Cu 0.091 Mn 0.375 Ti 0.2 Sb 0.0833 Capacity-cycle number curve of sodium half-cell made of O2 positive electrode material.

[0057] Figure 3E The method of using Na according to the embodiment of the present disclosure is shown. 0.96 Ca 0.04 Ni 0.25 Cu 0.125 Mn 0.375 Ti 0.166 Sb 0.08 Voltage-time curve of sodium half-cell made of 3O2 positive electrode material.

[0058] Figure 3F The method of using Na according to the embodiment of the present disclosure is shown. 0.96 Ca 0.04 Ni 0.25 Cu 0.125 Mn 0.375 Ti 0.166 Sb 0.08Capacity-cycle number curve of sodium half-cell made of 3O2 positive electrode material.

[0059] Figure 3G The method of using Na according to the embodiment of the present disclosure is shown. 0.8 Ca 0.2 Ni 0.6 Mn 0.2 Ti 0.2 Voltage-time curve of sodium half-cell made of O2 positive electrode material.

[0060] Figure 3H The method of using NaNi according to an embodiment of the present disclosure is shown. 1 / 6 Mg 1 / 6 Cu 1 / 6 Co 1 / 6 Fe 1 / 6 Mn 1 / 8 Ti 1 / 8 Voltage-time curve of sodium half-cell made of O2 positive electrode material.

[0061] Figure 3I The positive electrode a according to the embodiment of the present disclosure is shown 0.96 Ca 0.02 Ni 0.45 Cu 0.1 Mn 0.25 Ti 0.1 Sb 0.1 Voltage-time curve of sodium half-cell made of O2 positive electrode material.

[0062] Figure 3J The cathode Na 0.97 Ca 0.03 Li 0.02 Ni 0.5 Cu 0.05 Mn 0.2 Ti 0. 1Sb 0.13 Voltage-time curve of sodium half-cell made of O2 positive electrode material.

[0063] Figure 4A The Na according to the embodiment of the present disclosure is shown 0.97 Ca 0.03 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05 FESEM image of the O2 cathode material composition.

[0064] Figure 4B The Na according to the embodiment of the present disclosure is shown0.98 Ni 0.25 Cu 0.091 Mn 0.375 Ti 0.2 Sb 0.0833 FESEM image of the O2 cathode material composition.

[0065] Figure 4C The Na according to the embodiment of the present disclosure is shown 0.96 Ca 0.04 Ni 0.25 Cu 0.125 Mn 0.375 Ti 0.166 Sb 0.083 FESEM image of the O2 cathode material composition.

[0066] Figure 4D The Na according to the embodiment of the present disclosure is shown 0.96 Ca 0.02 Ni 0.45 Cu 0.1 Mn 0.25 Ti 0.1 Sb 0.1 FESEM image of the O2 cathode material composition. DETAILED DESCRIPTION

[0067] The following description includes a preferred best mode of an embodiment of the present invention. It is clear from the description of the present invention that the present invention is not limited to the embodiment shown, but the present invention also includes various modifications and embodiments thereof. Therefore, this description should be regarded as illustrative rather than restrictive. Although the present invention can have various modifications and alternative structures, it should be understood that this does not mean that the present invention is limited to the specific form disclosed. On the contrary, the present invention will cover all modifications, alternative structures and equivalents that fall within the spirit and scope of the present invention as defined by the claims.

[0068] In any embodiment described herein, the open-ended terms "comprising," etc. (which are synonymous with "including," "having," and "characterized by") may be replaced by the corresponding partially closed phrases "consisting essentially of," etc. or the corresponding closed phrases "consisting of," etc.

[0069] As used herein, the singular forms "a," "an," and "the" refer to both the singular and the plural, unless expressly stated to be directed to the singular only.

[0070] According to an embodiment of the present invention, a cathode composition is synthesized by a simple and easy solid-state method. The precursors weighed in stoichiometric ratios are thoroughly mixed and ground or ball-milled in an agate mortar for 30 minutes to 5 hours, and calcined at 400°C to 700°C under air or argon atmosphere for 2 hours to 10 hours, followed by intermediate grinding or ball milling for 1 hour to 10 hours. The ground powder is calcined at 700°C to 1000°C under air or argon atmosphere for 5 hours to 20 hours. After cooling, the obtained cathode composition is stored in an argon glove box to prevent moisture.

[0071] Preferably, the mixture of precursor materials includes Na2CO3, Li2CO3, LiOH.xH2O, NiO, NiCO3, Ni(OH) 2.x One or more compounds selected from the group consisting of H2O, MnO2, MnO, Mn2O3, Mg(OH)2, MgO, TiO2, Al(OH)3, Al2O3, CuO, ZnO, Sb2O3, and Sb2O5.

[0072] Figure 1 A schematic diagram of a sodium ion battery 100 according to an embodiment of the present invention is shown. The sodium ion battery consists of two electrodes, a positive electrode 106 and a hard carbon negative electrode 102, separated by a porous separator 104 and immersed in a non-aqueous sodium ion conductive liquid electrolyte 108, which uses a sodium salt in a mixture of an organic solvent and additives.

[0073] According to an embodiment of the present invention, a positive electrode is prepared by solvent casting a slurry of an active positive electrode material 106, conductive carbon, a binder, and a solvent. The conductive carbon used is Super P, the binder is PVDF, and N-methyl-2-pyrrolidone (NMP) is used as a solvent. The positive electrode material is coated with aluminum foil (112); the negative electrode is coated with aluminum or copper foil (110). The slurry is then cast on the aluminum foil, which is then kept in a drying oven at 120°C for 12 hours to obtain the positive electrode.

[0074] According to an embodiment of the present invention, when charged sodium ions move from the positive electrode (106) NaMO2 layered structure to the negative electrode (102) side, during discharge, the sodium ions move back to the MO2 main framework, but the electrons are converted to the external circuit.

[0075] Figure 2A The cathode material Na according to the embodiment of the present invention is shown. 0.97 Ca 0.03 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05X-ray diffraction pattern of O2. X-ray diffraction (XRD) is a rapid method for determining the formation of a desired cathode material composition by crystal structure analysis. In one embodiment of the present invention, the cathode material composition is characterized by a Bruker D8ADVANCE diffractometer. According to one embodiment of the present invention, the diffraction peak corresponds to a layered compound and no other impurity peaks are observed. The high-intensity peak confirms that the material is crystalline. The XRD pattern shows that the cathode composition is a single-phase O3-type layered structure with a space group of R-3m.

[0076] Figure 2B The water-treated Na 0.97 Ca 0.03 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05 X-ray diffraction pattern of an O2 cathode material. The sample was stirred in water for 30 minutes. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern shows a single-phase O3-type layered structure with space group R-3m.

[0077] Figure 2C shows Na according to an embodiment of the present invention 0.98 Ni 0.25 Cu 0.091 Mn 0.375 Ti 0.2 Sb 0.0833 X-ray diffraction pattern of the O2 cathode material. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern reveals a single-phase O3-type layered structure with space group R-3m.

[0078] Figure 2D The water-treated Na 0.98 Ni 0.25 Cu 0.091 Mn 0.375 Ti 0.2 Sb 0.0833 X-ray diffraction pattern of an O2 cathode material. The sample was stirred in water for 30 minutes. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern shows a single-phase O3-type layered structure with space group R-3m.

[0079] Figure 2E shows Na according to an embodiment of the present invention 0.96 Ca0.04 Ni 0.25 Cu 0.125 Mn 0.375 Ti 0.166 Sb 0.083 X-ray diffraction pattern of the O2 cathode material. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern reveals a single-phase O3-type layered structure with space group R-3m.

[0080] Figure 2F The water-treated Na 0.96 Ca 0.04 Ni 0.25 Cu 0.125 Mn 0.375 Ti 0.166 Sb 0.083 X-ray diffraction pattern of an O2 cathode material. The sample was stirred in water for 30 minutes. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern shows a single-phase O3-type layered structure with space group R-3m.

[0081] Figure 2G shows Na according to an embodiment of the present invention 0.8 Ca 0.2 Ni 0.6 Mn 0.2 Ti 0.2 X-ray diffraction pattern of the O2 cathode material. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern reveals a single-phase O3-type layered structure with space group R-3m.

[0082] Figure 2H The water-treated Na 0.8 Ca 0.2 Ni 0.6 Mn 0.2 Ti 0.2 X-ray diffraction pattern of an O2 cathode material. The sample was stirred in water for 30 minutes. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern shows a single-phase O3-type layered structure with space group R-3m.

[0083] Figure 2I The NaNi according to an embodiment of the present invention is shown. 1 / 6 Mg 1 / 6 Cu 1 / 6 Co 1 / 6 Fe 1 / 6 Mn1 / 8 Ti 1 / 8 X-ray diffraction pattern of the O2 cathode material. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern reveals a single-phase O3-type layered structure with space group R-3m.

[0084] Figure 2J The water-treated NaNi according to an embodiment of the present invention is shown. 1 / 6 Mg 1 / 6 Cu 1 / 6 Co 1 / 6 Fe 1 / 6 Mn 1 / 8Ti 1 / 8 X-ray diffraction pattern of an O2 cathode material. The sample was stirred in water for 30 minutes. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern shows a single-phase O3-type layered structure with space group R-3m.

[0085] Figure 2K shows Na according to an embodiment of the present invention 0.95 Ca 0.05 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05 X-ray diffraction pattern of the O2 cathode material. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern reveals a single-phase O3-type layered structure with space group R-3m.

[0086] Figure 2L The water-treated Na 0.95 Ca 0.05 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05 X-ray diffraction pattern of an O2 cathode material. The sample was stirred in water for 30 minutes. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern shows a single-phase O3-type layered structure with space group R-3m.

[0087] Figure 2M shows Na according to an embodiment of the present invention 0.95 Ca 0.05 Ni 0.6 Mn0.2 Ti 0.1 Sb 0.1 X-ray diffraction pattern of the O2 cathode material. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern reveals a single-phase O3-type layered structure with space group R-3m.

[0088] Figure 2N The water-treated Na 0.95 Ca 0.05 Ni 0.6 Mn 0.2 Ti 0.1 Sb 0.1 X-ray diffraction pattern of an O2 cathode material. The sample was stirred in water for 30 minutes. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern shows a single-phase O3-type layered structure with space group R-3m.

[0089] Figure 2O shows Na according to an embodiment of the present invention 0.96 Ca 0.02 Ni 0.45 Cu 0.1 Mn 0.25 Ti 0.1 Sb 0.1 X-ray diffraction pattern of the O2 cathode material. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern reveals a single-phase O3-type layered structure with space group R-3m.

[0090] Figure 2P The water-treated Na 0.96 Ca 0.02 Ni 0.45 Cu 0.1 Mn 0.25 Ti 0. 1Sb 0.1 X-ray diffraction pattern of an O2 cathode material. The sample was stirred in water for 30 minutes. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern shows a single-phase O3-type layered structure with space group R-3m.

[0091] Figure 2Q shows Na according to an embodiment of the present invention 0.97 Ca 0.03 Li 0.02 Ni 0.5 Cu 0.05 Mn0.2 Ti 0.1 Sb 0.13 X-ray diffraction pattern of the O2 cathode material. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern reveals a single-phase O3-type layered structure with space group R-3m.

[0092] Figure 2R The water-treated Na 0.97 Ca 0.03 Li 0.02 Ni 0.5 Cu 0.05 Mn 0. 2Ti 0.1 Sb 0.13 X-ray diffraction pattern of an O2 cathode material. The sample was stirred in water for 30 minutes. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern shows a single-phase O3-type layered structure with space group R-3m.

[0093] Figure 2S The NaCu according to an embodiment of the present invention is shown 0.1 Ni 0.15 Fe 0.30 Mn 0.35 Ti 0.05 Sb 0.02 X-ray diffraction pattern of the O2 cathode material. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern reveals a single-phase O3-type layered structure with space group R-3m. Figure 2T The aqueous treated NaCu 0.1 Ni 0.15 Fe 0.30 Mn 0.35 Ti 0.05 Sb 0.02 X-ray diffraction pattern of an O2 cathode material. The sample was stirred in water for 30 minutes. The diffraction peaks correspond to layered compounds, with no other impurity peaks observed. The high-intensity peaks confirm the crystalline nature of the material. The XRD pattern shows a single-phase O3-type layered structure with space group R-3m.

[0094] Figure 3A shows the 0.97 Ca 0.03 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05Figure 2 shows a voltage-time graph of a sodium half-cell made of an O2 positive electrode material. According to an embodiment of the present invention, the active positive electrode material composition was characterized by a BioLogic BCS-800 series battery cycler. The voltage-time graph helps to determine the charging time period, voltage window, and cycling stability of the positive electrode active material. Within the cell voltage window of 2V to 4V, the present invention exhibits a charge capacity and discharge capacity of ~(approximately) 152mAh / g and ~123mAh / g, respectively, at a current density equivalent to C / 25. ~0.52 moles of sodium ions are reversibly embedded in the crystal structure. The discharge capacity decay over the first two cycles was 1.02%, and the coulombic efficiency was 81%.

[0095] Figure 3B Shown with Na 0.97 Ca 0.03 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05 Specific capacity versus cycle number curve for a sodium half-cell fabricated with an O2 positive electrode material. According to embodiments of the present invention, capacity-cycling helps determine the voltage window and cycling stability of the positive electrode active material. Within the cell voltage window of 2V to 4V, the present invention exhibits charge and discharge capacities of ~152 mAh / g and ~123 mAh / g, respectively, at a current density equivalent to C / 25. Capacity retention after 20 cycles is 93%.

[0096] Figure 3C Shown with Na 0.98 Ni 0.25 Cu 0.091 Mn 0.375 Ti 0.2 Sb 0.0833 Voltage-time curve of a sodium half-cell made with O2 positive electrode material. According to embodiments of the present invention, the voltage-time curve helps determine the charging period, voltage window, and cycling stability of the positive electrode active material. Within the cell voltage window of 2V to 4V, the present invention exhibits a charge capacity and discharge capacity of ~141.27 mAh / g and ~140.956 mAh / g, respectively, at a current density equivalent to C / 25. ~0.6 moles of sodium ions are reversibly embedded in the crystal structure. The discharge capacity decay over the first two cycles was 1.03%, and the Coulombic efficiency was 99%.

[0097] Figure 3D Shown with Na 0.98 Ni 0.25 Cu 0.091 Mn 0.375 Ti 0.2 Sb 0.0833Specific capacity versus cycle number curve for a sodium half-cell fabricated with an O2 positive electrode material. According to embodiments of the present invention, capacity-cycling analysis helps determine the voltage window and cycling stability of the positive electrode active material. Within the cell voltage window of 2V to 4V, the present invention exhibits charge and discharge capacities of ~141.27 mAh / g and ~140.95 mAh / g, respectively, at a current density equivalent to C / 25. Capacity retention after 16 cycles is 95%.

[0098] Figure 3E Shown with Na 0.96 Ca 0.04 Ni 0.25 Cu 0.125 Mn 0.375 Ti 0.166 Sb 0.083 Voltage-time curve of a sodium half-cell fabricated with an O2 positive electrode material. According to embodiments of the present invention, the voltage-time curve helps determine the charging period, voltage window, and cycling stability of the positive electrode active material. Within the cell voltage window of 2V to 4V, the present invention exhibits charge and discharge capacities of ~121 mAh / g and ~114.9 mAh / g, respectively, at a current density equivalent to C / 25. ~0.6 moles of sodium ions are reversibly embedded in the crystal structure. The discharge capacity decay over the first two cycles was 1.014%, and the Coulombic efficiency was 94%.

[0099] Figure 3F Shown with Na 0.96 Ca 0.04 Ni 0.25 Cu 0.125 Mn 0.375 Ti 0.166 Sb 0.083 Specific capacity versus cycle number curve for a sodium half-cell fabricated with an O2 positive electrode material. According to embodiments of the present invention, capacity-cycling analysis helps determine the voltage window and cycling stability of the positive electrode active material. Within the cell voltage window of 2V to 4V, the present invention exhibits charge and discharge capacities of ~121 mAh / g and ~114.9 mAh / g, respectively, at a current density equivalent to C / 25. Capacity retention after 20 cycles is 90%.

[0100] Figure 3G Shown with Na 0.8 Ca 0.2 Ni 0.6 Mn 0.2 Ti 0.2Voltage-time curve of a sodium half-cell fabricated with an O2 positive electrode material. According to embodiments of the present invention, the voltage-time curve helps determine the charging period, voltage window, and cycling stability of the positive electrode active material. Within the cell voltage window of 2V to 4V, the present invention exhibits charge and discharge capacities of ~127 mAh / g and ~109 mAh / g, respectively, at a current density equivalent to C / 25. ~0.46 moles of sodium ions are reversibly embedded in the crystal structure. The discharge capacity decay over the first two cycles was 1.016%, and the Coulombic efficiency was 86%.

[0101] Figure 3H Shown with NaNi 1 / 6 Mg 1 / 6 Cu 1 / 6 Co 1 / 6 Fe 1 / 6 Mn 1 / 8 Ti 1 / 8 Voltage-time curve of a sodium half-cell fabricated with an O2 positive electrode material. According to embodiments of the present invention, the voltage-time curve helps determine the charging period, voltage window, and cycling stability of the positive electrode active material. Within the cell voltage window of 2V to 4V, the present invention exhibits charge and discharge capacities of ~103 mAh / g and ~90 mAh / g, respectively, at a current density equivalent to C / 25. ~0.38 moles of sodium ions are reversibly embedded in the crystal structure. The discharge capacity decay over the first two cycles was 1.013%, and the Coulombic efficiency was 86%.

[0102] Figure 3I Shown with Na 0.96 Ca 0.02 Ni 0.45 Cu 0.1 Mn 0.25 Ti 0.1 Sb 0.1 Voltage-time curve of a sodium half-cell fabricated with an O2 positive electrode material. According to embodiments of the present invention, the voltage-time curve helps determine the charging period, voltage window, and cycling stability of the positive electrode active material. Within the cell voltage window of 2V to 4.4V, the present invention exhibits charge and discharge capacities of ~138 mAh / g and ~117 mAh / g, respectively, at a current density equivalent to C / 25. ~0.52 moles of sodium ions are reversibly embedded in the crystal structure. The discharge capacity decay over the first two cycles was 1.015%, and the Coulombic efficiency was 84%.

[0103] Figure 3J Shown with Na 0.97 Ca 0.03 Li 0.02 Ni 0.5 Cu 0.05 Mn 0.2 Ti0.1 Sb 0.13 Figure 2 shows a voltage-time curve of a sodium half-cell fabricated with a 1.5-μm O cathode material. According to embodiments of the present invention, the voltage-time curve helps determine the charging period, voltage window, and cycling stability of the cathode active material. Within the cell voltage window of 2V to 4V, the present invention exhibits charge and discharge capacities of ~126 mAh / g and ~118 mAh / g, respectively, at a current density equivalent to C / 25. ~0.50 moles of sodium ions are reversibly embedded in the crystal structure. The discharge capacity decay over the first two cycles was 1.02%, and the Coulombic efficiency was 93%.

[0104] Figure 4A shows Na according to an embodiment of the present invention 0.97 Ca 0.03 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05 FESEM image of an O2 positive electrode active material composition. The morphology of the positive electrode active material composition was characterized using a Carl Zeiss 130VP field emission scanning electron microscope (FESEM). In one embodiment of the present invention, the microscopic image shows that the solid-state synthesized positive electrode active material composition exhibits irregular granular and polygonal granular shapes. Furthermore, the positive electrode active material composition comprises various morphologies, such as, but not limited to, rhombuses, hexagons, polygons, cubes, spheres, and elongated hexagons.

[0105] Figure 4B shows Na according to an embodiment of the present invention 0.98 Ni 0.25 Cu 0.091 Mn 0.375 Ti 0.2 Sb 0.0833 FESEM image of an O2 positive electrode active material composition. The microscopic image shows that the solid-state synthesized positive electrode active material composition exhibits irregular granular morphology. Furthermore, the positive electrode active material composition comprises various morphologies, such as, but not limited to, rhombuses, hexagons, cubes, polygons, spheres, and elongated hexagons.

[0106] Figure 4C shows Na according to an embodiment of the present invention 0.96 Ca 0.04 Ni 0.25 Cu 0.125 Mn 0.375 Ti 0.166 Sb 0.083FESEM image of an O2 positive electrode active material composition. The microscopic image shows that the solid-state synthesized positive electrode active material composition exhibits flaky, granular morphology. Furthermore, the positive electrode active material composition comprises various morphologies, such as, but not limited to, rhombuses, hexagons, cubes, spheres, polygons, and elongated hexagons.

[0107] Figure 4D shows Na according to an embodiment of the present invention 0.96 Ca 0.02 Ni 0.45 Cu 0.1 Mn 0.25 Ti 0.1 Sb 0.1 FESEM image of an O2 positive electrode active material composition. The microscopic image shows that the solid-state synthesized positive electrode active material composition exhibits irregular granular morphology. Furthermore, the positive electrode active material composition comprises various morphologies, such as, but not limited to, rhombuses, hexagons, cubes, spheres, polygons, and elongated hexagons.

[0108] While the invention has been described in connection with what are presently considered to be the most practical embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but on the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0109] This description uses examples to disclose the invention, including the best mode, and also to enable those skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined in the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with substantial differences from the literal language of the claims. Example

[0110] The following examples are given by way of illustration of the working of the invention in actual practice and therefore should not be construed as limiting the scope of the invention. Example 1

[0111] by Na 0.97 Ca 0.03 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05A multivalent cathode material composition represented by O2. According to an embodiment of the present invention, the composition is prepared by a solid-state method. Stoichiometric precursors CaCO3, NiO, CuO, Al2O3, MnO2, TiO2, Sb2O3, and Na2CO3 are thoroughly mixed and ground in an agate mortar for 30 minutes. The mixture is then calcined in air at 400°C for 2 hours, followed by intermediate ball milling for 3 hours. The ground powder is then calcined in air at 700°C for 20 hours. Figure 2A The X-ray diffraction (XRD) pattern shown in confirms that the composition is a single-phase structure, and all peaks match O3, which belongs to a rhombohedral crystal structure with a space group R-3m. The moisture sensitivity was evaluated by immersing the positive electrode material sample in water for 30 minutes to 10 hours, then filtering and drying in an oven at 100°C. According to an embodiment of the present invention, Figure 4A The field emission scanning electron microscope (FESEM) micrograph shown in Figure 3 shows that the morphology of the cathode material composition exhibits irregular flakes. According to an embodiment of the present invention, the voltage versus time graph shown in Figure 3A shows that within the cell voltage window of 2V to 4V, the sodium half-cell fabricated using the cathode material exhibits a charge capacity and discharge capacity of ˜152 mAh / g and ˜123 mAh / g, respectively, at a current density equivalent to C / 25. Example 2

[0112] by Na 0.98 Ni 0.25 Cu 0.091 Mn 0.375 Ti 0.2 Sb 0.0833 A multivalent cathode material composition represented by O2. According to an embodiment of the present invention, the composition is prepared by a solid-state method. Stoichiometric precursors NiO, CuO, Mn2O3, TiO2, Sb2O3, and Na2CO3 are thoroughly mixed and ball-milled for 10 hours, and calcined in air at 700°C for 10 hours, followed by intermediate ball milling for 10 hours. The ground powder is calcined in air at 800°C for 10 hours. Figure 2C The XRD pattern shown in confirms that the composition is a single-phase structure, and all peaks match O3, which belongs to a rhombohedral crystal structure with space group R-3m. The moisture sensitivity was evaluated by immersing the sample in water for 30 minutes to 10 hours, then filtering and drying in an oven at 100°C. According to an embodiment of the present invention, Figure 4B The FESEM micrographs shown in show that the morphology of the composition has an irregular shape. According to an embodiment of the present invention, Figure 3CThe voltage versus time plots shown in indicate that within the cell voltage window of 2 V to 4 V, the sodium half-cell fabricated with the cathode material exhibits a charge and discharge capacity of ∼141 mAh / g and ∼140 mAh / g, respectively, at a current density equivalent to C / 25. Example 3

[0113] by Na 0.96 Ca 0.04 Ni 0.25 Cu 0.125 Mn 0.375 Ti 0.166 Sb 0.083 The multivalent positive electrode material composition represented by O2 is prepared by a solid-state method according to an embodiment of the present invention. The precursors CaCO3, Ni(OH) 2.x H2O, CuO, MnO2, TiO2, Sb2O3 and Na2CO3 were thoroughly mixed and ball-milled for 2 hours and calcined at 500°C in air for 3 hours, followed by intermediate ball milling for 2 hours. The ground powder was calcined at 800°C in air for 15 hours. Figure 2E The XRD pattern shown in confirms that the composition is a single-phase structure, and all peaks match O3, which belongs to a rhombohedral crystal structure with space group R-3m. The moisture sensitivity was evaluated by immersing the sample in water for 30 minutes to 10 hours, then filtering and drying in an oven at 100°C. According to an embodiment of the present invention, Figure 4C The FESEM micrograph shown in FIG shows that the morphology of the composition is irregular flake-like. According to an embodiment of the present invention, Figure 3E The voltage versus time graph shown in shows that a sodium half-cell fabricated with the positive electrode material exhibits a charge capacity and a discharge capacity of ∼121 mAh / g and ∼114 mAh / g, respectively, at a current density equivalent to C / 25 within the cell voltage window of 2 V to 4 V. Example 4

[0114] by Na 0.96 Ca 0.02 Ni 0.45 Cu 0.1 Mn 0.25 Ti 0.1 Sb 0.1 A multivalent cathode material composition represented by O2. According to an embodiment of the present invention, the composition is prepared by a solid-state method. Precursors CaCO3, NiCO3, CuO, MnO2, TiO2, Sb2O3, and Na2CO3, weighed in stoichiometric proportions, are thoroughly mixed and ball-milled for 5 hours, and calcined in air at 600°C for 5 hours, followed by intermediate ball milling for 5 hours. The ground powder is calcined in air at 900°C for 5 hours. Figure 2O The XRD pattern shown in confirms that the composition is a single-phase structure, and all peaks match O3, which belongs to a rhombohedral crystal structure with space group R-3m. The moisture sensitivity was evaluated by immersing the sample in water for 30 minutes to 10 hours, then filtering and drying in an oven at 100°C. According to an embodiment of the present invention, Figure 4D The FESEM micrograph shown in FIG shows that the morphology of the composition is irregular flake-like. According to an embodiment of the present invention, Figure 3I The voltage versus time graph shown in shows that a sodium half-cell fabricated with the positive electrode material exhibits a charge capacity and a discharge capacity of ∼138 mAh / g and ∼117 mAh / g, respectively, at a current density equivalent to C / 25 within the cell voltage window of 2 V to 4 V. Example 5

[0115] According to an embodiment of the present invention, Na 0.8 Ca 0.2 Ni 0.6 Mn 0.2 Ti 0.2 The O2-represented multivalent cathode material composition was prepared by a solid-state method. Precursors CaCO3, NiO, CuO, MnO2, TiO2, Sb2O3, and Na2CO3, weighed in stoichiometric proportions, were thoroughly mixed and ground in an agate mortar for 3 hours. The mixture was then calcined in air at 500°C for 3 hours, followed by intermediate ball milling for 5 hours. The ground powder was then calcined in air at 850°C for 20 hours. Figure 2G The XRD pattern shown in confirms that the composition is a single-phase structure, and all peaks match O3, which belongs to a rhombohedral crystal structure with space group R-3m. The moisture sensitivity was evaluated by immersing the sample in water for 30 minutes to 10 hours, then filtering and drying in an oven at 100°C. According to an embodiment of the present invention, Figure 3G The voltage versus time graph shown in shows that a sodium half-cell fabricated with the positive electrode material exhibits a charge capacity and a discharge capacity of ∼127 mAh / g and ∼109 mAh / g, respectively, at a current density equivalent to C / 25 within the cell voltage window of 2 V to 4 V. Example 6

[0116] By Nani 1 / 6 Mg 1 / 6 Cu 1 / 6 Co 1 / 6 Fe 1 / 6 Mn 1 / 8 Ti 1 / 8A multivalent cathode material composition represented by O2. According to an embodiment of the present invention, the composition is prepared by a solid-state method. Precursors NiO, MgO, CuO, CO3O4, MnO2, Fe3O4, TiO2, Sb2O3, and Na2CO3, weighed in stoichiometric proportions, are thoroughly mixed and ground in an agate mortar for 1 hour, calcined in air at 400°C for 2 hours, and then intermediately ball-milled for 3 hours. The ground powder is calcined in air at 700°C for 20 hours. Figure 2I The XRD pattern shown in confirms that the composition is a single-phase structure, and all peaks match O3, which belongs to a rhombohedral crystal structure with space group R-3m. The moisture sensitivity was evaluated by immersing the sample in water for 30 minutes to 10 hours, then filtering and drying in an oven at 100°C. According to an embodiment of the present invention, Figure 3H The voltage versus time graph shown in shows that a sodium half-cell fabricated with the positive electrode material exhibits a charge capacity and a discharge capacity of ∼103 mAh / g and ∼90 mAh / g, respectively, at a current density equivalent to C / 25 within the cell voltage window of 2 V to 4 V. Example 7

[0117] by Na 0.97 Ca 0.03 Li 0.02 Ni 0.5 Cu 0.05 Mn 0.2 Ti 0.1 Sb 0.13 A multivalent cathode material composition represented by O2. According to an embodiment of the present invention, the composition is prepared by a solid-state method. Precursors CaCO3, Li2CO3, NiO, CuO, MnO2, TiO2, Sb2O3, and Na2CO3, weighed in stoichiometric proportions, are thoroughly mixed and ball-milled for 10 hours and calcined in air at 700°C for 10 hours, followed by intermediate ball milling for 10 hours. The ground powder is calcined in air at 800°C for 10 hours. Figure 2A The XRD pattern shown in confirms that the composition is a single-phase structure, with all peaks matching those of O3, a rhombohedral crystal structure with space group R-3m. Moisture sensitivity was evaluated by immersing the sample in water for 30 minutes to 10 hours, followed by filtration and oven drying at 100°C. The voltage versus time graph shown in FIG3Q shows that a sodium half-cell fabricated with the positive electrode material exhibits a charge capacity and discharge capacity of ~126 mAh / g and ~118 mAh / g, respectively, at a current density equivalent to C / 25 within a cell voltage window of 2 V to 4 V, according to an embodiment of the present invention.

[0118] The present invention is not limited to these materials, and examples of alternative positive electrodes include Na 0.95 Ca0.05 Ni 0.4 Cu 0.1 Al 0.05 Mn 0. 3Ti 0.1 Sb 0.05 O2 Na 0.99 Ca 0.01 Ni 0.4 Cu 0.1 Al 0.05 Mn 0.3 Ti 0.1 Sb 0.05 O2 Na 0.94 Ca 0.03 Ni 0.5 Cu 0.1 Mn 0.1 Ti 0.1 Sb 0.2 O2 Na 0.95 Ca 0.05 Ni 0.6 Mn 0.2 Ti 0.1 Sb 0.1 O2 NaCa 0.03 Cu 0.1 Ni 0.3 Fe 0.32 Mn 0.25 Ti 0.05 O2 NaCu 0.1 Ni 0.15 Fe 0.30 Mn 0.35 Ti 0.05 Sb 0.02 O2 Na 0.98 Ca 0.02 Ni 1 / 7 Cu 1 / 7 Al 1 / 7 Co 1 / 7 Fe 1 / 7 Mn 1 / 7 Ti 1 / 7 O2 Na 0.97 Ca 0.03 Ni 0.12 Cu 0.15 Mn 0.5 Ti 0.23 O2 Beneficial effects of the present invention

[0119] The main advantages of the present invention are: 1. The cathode material composition is moisture and air stable. 2. The positive electrode material has improved cycle performance and high voltage performance. 3. The positive electrode material composition can be used in the battery industry. 4. The composition formula contains abundant and low-cost elements. 5. The cathode material composition can be produced on a large scale and has strong adaptability.

Claims

1. A compound having the formula Na x A z Ni i M y Mn j Ti k Sb f O2 air and moisture stable layered oxide cathode materials, which (i+j+k+f+y=1), 0.7≤x≤1, 0≤z≤0.2, 0≤y≤0.5, 0.1≤i≤0.6, 0.1≤j≤0.5, 0.05≤k≤0.4, 0≤f≤0.2, a) wherein A is an alkali metal or alkaline earth metal selected from a divalent Ca element or a monovalent Li element; b) M is a divalent element or a trivalent element selected from Fe, Mg, Zn, Cu, Al, Co, or a combination thereof, having oxidation states of +2 and +3, respectively; c) Ni is a divalent element with an oxidation state of +2; d) Mn and Ti are tetravalent elements in the oxidation state +4; and e) Sb is a pentavalent element / trivalent element having an oxidation state of +5 / +3.

2. The positive electrode material according to claim 1, wherein The positive electrode material is selected from Hand 0.97 Attached 0.03 Would 0.4 Cu 0.1 Al 0.05 Mn 0.3 A 0.1 Sb 0.05 O2: Hand 0.95 Attached 0.05 Would 0.4 Cu 0.1 Al 0.05 Mn 0.3 A 0.1 Sb 0.05 O2: Hand 0.99 Attached 0.01 Would 0.4 Cu 0.1 Al 0.05 Mn 0.3 A 0.1 Sb 0.05 O2: Hand 0.94 Attached 0.03 Would 0.5 Cu 0.1 Mn 0.1 A 0.1 Sb 0.2 O2: In 0.95 Ca 0.05 Ni 0.6 Mn 0.2 A 0.1 Sb 0.1 O2; Hand 0.96 Attached 0.02 Would 0.45 Cu 0.1 Mn 0.25 A 0.1 Sb 0.1 O2: In 0.8 Ca 0.2 Ni 0.6 Mn 0.2 A 0.2 O2; So 0.97 Approx 0.03 Li 0.02 Ni 0.5 Cu 0.05 Mr 0.2 Tea 0.1 Sb 0.13 O2; NaCa 0.03 The 0.1 Aunt 0.3 Fe 0.32 Mn 0.25 Water 0.05 O2; NaCu 0.1 In 0.15 Want 0.30 Mn 0.35 Of 0.05 Sb 0.02 O2; Pretty 1 / 6 Mg 1 / 6 Cu 1 / 6 Co 1 / 6 Feb 1 / 6 Mr 1 / 8 Tea 1 / 8 O2; So 0.98 Approx 0.02 Ni 1 / 7 Cu 1 / 7 Al 1 / 7 Co 1 / 7 Feb 1 / 7 Mr 1 / 7 Tea 1 / 7 O2; Hand 0.96 Attached 0.04 Would 0.25 Cu 0.125 Mn 0.375 A 0.166 Sb 0.083 O2: Na 0.98 Ni 0.25 Cu 0.091 Mn 0.375 Ti 0.2 Sb 0.0833 O2; or Hand 0.97 Attached 0.03 Would 0.12 Cu 0.15 Mn 0.5 A 0.23 O2。 3. The positive electrode material according to claim 2, wherein The positive electrode material is an O3 type layered structure.

4. The positive electrode material according to claim 2, wherein The positive electrode material is single-phase and has a rhombohedral crystal structure and an R-3m space group.

5. The positive electrode material according to claim 2, wherein The cathode material exhibits a capacity between 70 mAh / g and 195 mAh / g.

6. The positive electrode material according to claim 2, wherein The positive electrode material operates in a voltage range of 2V to 4.5V.

7. A sodium ion battery (100) comprising the air and moisture stable layered oxide cathode material of claim 1, comprising: (i) a positive electrode (106), the positive electrode (106) comprising a single-phase positive electrode material according to any one of claims 1 or 2; (ii) negative electrode (102); (iii) a non-aqueous electrolyte (108); and a separator (104).

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